This invention relates to a wall structure capable of use for the top story of a multiple story building and, more specifically, to a prefabricated wall section in which the load-bearing studs are composed of steel of about 26 gauge thickness. These studs are secured vertically between a metal cap member and a floor track member which form the top and bottom of the wall section respectively.
Load-bearing wall sections commonly used in construction for the top floors of buildings are made either entirely of wood or of metal load-bearing studs having a thickness of 16 gauge or thicker. These metal wall sections suffer from the disadvantages of being heavy, unwieldy, and relatively unworkable with the hand tools usually found at a construction site. In addition, wood wall sections, though workable, are usually not uniform in size since variations in humidity affect the dimensions of wooden members. For this reason, a wooden wall section of uniform and stable characteristics is difficult to produce economically.
It has commonly been assumed by those in the construction industry that in order to meet the requirements of a load-bearing wall on the top story of a building, load-bearing studs composed of wood or of 16 gauge or thicker steel had to be employed. In some areas, the requirements for such a load-bearing wall are that, where the studs are 16 inches apart, the wall section be able to support a load on its top plate of at least 500 pounds per lineal foot and be able to withstand a wind load of at least 15 pounds per square foot, or that the wall section be able to support about 305 pounds per lineal foot and be able to withstand a wind load of at least 20 pounds per square foot. The disadvantages of wooden wall sections and heavy steel wall sections were previously accepted as unavoidable in order to obtain the required load-bearing characteristics for the wall section.
It has recently been discovered that the load-bearing studs of a multiple story dwelling, such as a two- or three-story house, can be made of 20 gauge steel.
I have now discovered that by making the top story walls of prefabricated metal load-bearing wall sections which are composed of steel load-bearing studs having a thickness of about 26 gauge, the entire wall sections, and also the entire building structure, acquires new and desirable characteristics and has many advantages over the wall sections previously employed while still exhibiting the necessary load-bearing characteristics. As used herein, "26 gauge" means the thickness of a member within the range of 25 to 27 gauge, 0.627 to 0.513 mm, or 0.0247 to 0.0202 inches. The steel referred to herein is hot dipped galvanized strip steel. An example of the type of steel employed is designated as ASTM-A446A. This steel has a yield strength of 33,000 psi and a tensile strength of 45,000 psi, thus rendering it suitable for use in both single-story and on the top floor in two-story construction.
Besides the usual advantages of repeatability of quality and accuracy and speed of construction attributable to most prefabricated structures, the main advantage of my invention is the achievement of a lightweight wall section which possesses the necessary load-bearing and other characteristics required for use in a load-bearing wall on the top story of a building under certain conditions. Such 26 gauge wall sections may be employed, for example, where the load on the top plate of the wall section is 500 pounds per lineal foot or less and where the wind load requirements are 15 pounds per square foot or less. At the same time, a lightweight wall section is provided and further advantages are evident when such a 26 gauge wall section is combined with load-bearing wall sections composed of 20 gauge studs on the lower stories of a multiple story building. That such 26 gauge wall sections meet such industry standards and requirements comes as a complete surprise to those in the building construction field. This invention is particularly useful in providing low cost housing and will result in substantial cost savings.
Typically a 10 foot wall section constructed of 20 gauge steel studs would weigh about 70 pounds, a similar wall section constructed of 2.times.4 wooden members would weigh about 134 pounds. But in this invention, a similar wall section constructed of 26 gauge steel studs typically weighs only about 40 pounds. This allows the 26 gauge sections to be easily carried and erected by hand, if desired, without the use of cranes and other heavy equipment while at the same time obtaining the necessary load-bearing characteristics for a top story wall.
It will be evident that such a 26 gauge wall section may be used as a load-bearing wall either in a single story building or on the top floor of a multiple story building. In multiple story buildings, the use of such 26 gauge wall sections on the top floor is especially advantageous when combined with load-bearing wall sections having 20 gauge load-bearing studs used in the lower floors. This combination results in an even greater reduction in the time required to construct such a multiple story building than if 26 gauge wall sections were used for the top story and wooden wall sections for the bottom stories.
The wall section of this invention has the additional advantage of being workable. That is, the members of a wall section constructed of 26 gauge steel may be cut at the construction site with a hand-held power saw or with metal shears, or the like. Pieces of the 26 gauge steel members may be bent and formed by hand in order to provide apertures or spaces in the members for the passage of previously installed plumbing and the like. Screws may also be conveniently driven through 26 gauge steel in order to secure wallboard and the like to the metal members. Nails may be driven through 26 gauge steel with a hammer into wooden members on the opposite side in order to secure the wooden members to the metal members.
The wall section of this invention is also flexible to such an extent that it will conform to irregularities in a concrete floor of the type which is often employed in the construction of residential homes. The type of irregularity referred to is not surface roughness but rather irregularities such as a 10 foot section of floor which is bowed so that its center is 1/2 inch higher than its ends.
In the best embodiment, the metal studs of the wall section of this invention are C-shaped. This C-shape of the metal studs gives the studs more load-bearing capability and also gives the flanges of the studs more rigidity so that the flanges are less likely to bend when screws and the like are driven through the flanges in order to secure a wallboard and the like to the flanges.
All of these advantages of lightweight, workability, flexibility, and maneuverability provide a substantial saving in cost to the constructor, thus enabling him to provide low cost housing. For example, a typical two-story residential house may be framed with the 20 gauge steel prefabricated wall sections on the lower story and 26 gauge wall sections on the upper story. The upper story would be framed in approximately one hour. This is about four to eight times faster than the same story could be framed if wooden wall sections constructed at the building site were employed. If prefabricated wooden wall sections are employed, extra cost to the contractor results from the extra weight of the wooden wall sections.